1. Field of the Invention
This invention relates to the field of heating, ventilation and air conditioning. More specifically, the invention comprises an electrical or electromechanical device that pulses the control line of an outdoor HVAC unit using the thermostat connections in order to indicate to a user which outdoor unit is associated with a particular indoor unit.
2. Description of Related Art
On most occasions heating, ventilation and air conditioning (HVAC) systems are set up with some components on the inside of a dwelling and some components on the outside. Such a system is often called a “split system.” FIG. 1 shows an example of a prior art split system. Inside unit 12 is located inside dwelling 10 while outside unit 14 is located outside the dwelling. The user controls, along with some type of temperature sensing device, are most often located in thermostat 22. Thermostat 22 has control lines 20 that run to control circuit 18 located within inside unit 12. Additional control lines 20 run from control circuit 18 to outside unit 14. In addition to control lines, refrigerant lines 16 run between inside unit 12 and outside unit 14. These lines carry the working fluid that circulates within the HVAC system.
In the case of large apartment complexes, multiple outside HVAC units are often located behind the building or on the roof. The presence of multiple outdoor units can can make it difficult to determine which outside unit corresponds to a particular inside unit. This becomes an issue when air conditioning repair personnel need to access the outside unit, but are faced with a multitude of nearly identical units with no method for deducing which is the correct unit. This scenario is shown in FIG. 4. In the example of FIG. 4, there are multiple outside units 14 behind a group of apartments 24. While FIG. 4 shows only six apartments 24, this situation becomes increasingly complex with the addition of more apartments (possibly occupying multiple floors).
Control and refrigerant lines run from the inside units 12 in each apartment 24 to an associated outside unit 14. Due to the quantity of lines and the fact that portions of the lines may be concealed, it would be a complicated if not impossible task to follow the lines from the apartment to the correct outside unit. Therefore, another method is typically used. The current solution requires the repair technician to bring an additional helper along for the repair job. The helper is tasked with quickly switching the air conditioning unit on and off from the thermostat inside the apartment while the technician waits outside listening for which unit comes on. (The task of the technician and helper could easily be switched). In the case of an air conditioning unit with a heat pump, a typical method is to switch the unit from heating to cooling or vice-versa. This action actuates the reversing valve contained in the outside unit. The actuation of the reversing valve causes a loud click which may be easily head.
Those skilled in the art will know that the reversing valve in a heat pump outdoor unit directs the refrigerant to flow in a selected direction. In one direction the system is in cooling mode. In this mode the coils and fan inside the dwelling act as the evaporator and the outside coils act as the condenser, thus cooling the air inside the dwelling. When the valve is reversed to heating mode, the coils switch roles and the air inside the dwelling is heated.
Actuating the reversing valve, again located in the outside air conditioning unit, creates a distinct clicking sound which can be heard by a helper standing near the outside units. The helper may then identify which outdoor unit is associated with the thermostat that the other technician is manipulating. A cooling-only system does not have a reversing valve. In the case of a cooling-only unit, briefly switching the air conditioning unit on activates the start contactor for the compressor. This also generates a loud clicking sound. The outside helper is then able to correctly identify the outside unit by listening for this clicking sound. Developing a method to identity the correct outside unit without the need for a second technician on-site would reduce the cost of HVAC repair work in multi-unit situations. A device that does this automatically would allow only one technician to go out to a site, thus leaving the second technician available for another job and only paying one technician for a job that now only requires one person. It is also important that the device used to actuate the reversing valve be compatible with most air conditioning units. The proposed invention allows a single technician to identify the outside unit and is compatible with both heat pump and cooling-only systems.